1. Field of the Invention (Technical Field)
The present invention relates to a device for sensing piano or keyboard key movement using a variety of sensors that are inserted into the piano or keyboard from atop the keys.
2. Description of Related Art
Note that the following discussion refers to a number of publications by author(s) and year of publication, and that due to recent publication dates certain publications are not to be considered as prior art vis-a-vis the present invention. Discussion of such publications herein is given for more complete background and is not to be construed as an admission that such publications are prior art for patentability determination purposes.
There have been many ways sought to detect key movement on pianos and keyboards. Electronic keyboards have the advantage of building in key detecting devices during its design and manufacturing. However, older electronic keyboards, organs, and pianos are not equipped with key detecting devices and circuitry. New pianos are coming equipped with sensor units, and older piano can be retrofitted with sensor units.
Even though there are many types of sensing technologies used in these retrofit systems, such as optical couplers, piezo-electric material, mechanical switches, and magnetic coupling, most retrofit units must be installed by disassembling pianos and installing the sensor strip internal to piano. Once inside the piano, there are other sensing techniques used by major piano manufacturers to sense key movement by placing sensors beneath the key to virtually anywhere along the key linkages points all the way up to the key-string striking mechanism.
U.S. Pat. No. 5,567,902, U.S. Pat. No. 5,231,283, and U.S. Pat. No. 5,763,806 use optical sensing techniques to sense key movement from underneath the piano keys. None of these however have addressed sensing the black and white keys from atop the keys. It would be desirable to have a portable key sensing apparatus for over the top of the keys.
U.S. Pat. No. 4,790,230 discloses a keyboard device that is mounted on top of a keyboard and uses optical sensing for detecting key movement. However, while the invention detects key movement, it uses the visible portions of the keys for key sensing. U.S. Pat. No. 4,790,230 also has a challenging effort to sense black key movement accurately due to the black color of the black keys. Further, U.S. Pat. No. 4,790,230 or any patent that uses optical techniques in a portable device for sensing key movement from atop the keys must attempt to correct or compensate key sensing information from ambient light, and in some cases protect the device from damage or erroneous key-note information due to high levels of ambient light.
When using optical sensing, it would be desirable to eliminate the ambient light problem in dealing with an optical sensing technique from atop the keyboard. It would also be desirable to not use the obvious visual portion of the keys to detect key movement because of this problem and to further reduce the size of the apparatus.